HEPATIC SPIRAL CT IN CHILDREN - SCAN DELAY TIME-ENHANCEMENT ANALYSIS

Purpose. To compare the effect of different time delays between contra st administration and the start of spiral CT scanning on hepatic enhan cement in children. Materials and methods. Forty-five children (2-9 ye ars old, mean 6 years) with no evidence of hepatic disease were examin ed with spiral CT. Sequential spiral scans through the entire liver we re performed following a uniphasic injection of nonionic contrast medi um. In group 1 scanning started at 80% of the contrast injection time, in group 2 scanning started at 100% of injection time, and in group 3 scanning started at 150% of injection time. Mean hepatic, aortic, and inferior vena caval enhancement were determined using regions-of-inte rest measurements. Results. Mean hepatic enhancement was 41.4, 47.0, a nd 40.6 HU for the 80%, 100%, and 150% injection times, respectively. Enhancement was significantly greater in the 100% injection time group (p < 0.05). A mean aortocaval difference of greater than 10 HU was pr esent in all examinations. Conclusion. Our results suggest that delayi ng the initiation of spiral CT scanning until the completion of the co ntrast injection increases hepatic enhancement in children. These data should help to improve the quality of hepatic spiral CT in pediatric patients.